1. Field of the Invention
The present invention relates to a movement route generating apparatus and a movement route generating method, and is preferably used particularly for an apparatus and method for generating a movement route along which a vehicle is to be guided to a target position by automatic driving.
2. Description of the Related Art
Conventional systems known in the related art automatically control the steering of a vehicle so that the vehicle travels on a predetermined movement route and stops at a target position such as a parking lot (see Japanese Unexamined Patent Application Publication Nos. 9-50596, 2014-34230, 2011-46335, 2004-338636, 2009-208742, 2004-291866, 2004-338638 and 2015-214223, and Japanese Patent No. 4092054, for example).
Japanese Unexamined Patent Application Publication No. 9-50596 discloses a technique that enables an agreeable guidance without rapid steering. Specifically, in Japanese Unexamined Patent Application Publication No. 9-50596, it is described that a smooth guidance trajectory with no abrupt curvature changes is made by calculating a guiding trajectory using a curve (clothoid curve), the curvature of which changes continuously, according to a slant distance from the current position of the vehicle to a target position of the vehicle, the position of an intersection formed by the axial line of the vehicle at the current position and the axial line of the vehicle at the target position, and an attitude angle formed by the axial line of the vehicle at the current position in the direction of travel and the axial line of the vehicle at the target position in the direction of travel.
Japanese Unexamined Patent Application Publication No. 2014-34230 discloses a technique that enables a target route to be easily generated even in a narrow parking lot. Specifically, if an attitude angle θ, which is formed by a direction of travel of the vehicle at a target position with a direction of travel of the vehicle at an initial position, and a stroke angle ϕ, which is formed by a line segment linking the initial position and the target position together with a direction of travel of the vehicle at the initial position, have a relationship in that θ is larger than or equal to 2ϕ, a target route is generated by combining a curve (clothoid curve) that varies in curvature with a curve (arc) that has a constant curvature. By contrast, if θ is smaller than 2ϕ, a target route is generated with respect to a first circumference C1 that passes through the initial position and is a tangent to the direction of travel of the vehicle at the initial position and a second circumference C2 that passes through the target position and is a tangent to the first circumference C1 and the line in the direction of travel of the vehicle at the target position.
In Japanese Unexamined Patent Application Publication No. 2011-46335, it is described that a parking route from a current position of a vehicle to a parking frame is generated by combining at least one of an arc, a clothoid curve, and a straight line.
In Japanese Unexamined Patent Application Publication No. 2004-338636 as well, it is described that a travel trajectory is set by combining at least one of an arc, a clothoid curve, and a straight line. In Japanese Unexamined Patent Application Publication No. 2004-338636, it is also described that if a vehicle position deviates from an initial travel trajectory, the method of calculating a new route to be set is changed depending on the amount of deviation. Specifically, if the amount of deviation is small, a route that returns to the previous route is calculated; and if the amount of deviation is large, a route that guides to the target position without considering the previous route is calculated again.
In Japanese Unexamined Patent Application Publication No. 2009-208742, it is described that if the center of a vehicle deviates from the center line of a guidance route, a route that returns to the guidance route is generated according to the movement speed of the vehicle and the steering angle of the vehicle at a reference position. In Japanese Unexamined Patent Application Publication No. 2009-208742, it is also described that even if the steering wheel of the vehicle at the current position is rotated up to a stroke end, but the vehicle will not be guided to the target parking position, it is decided that a guidance route cannot be set and parking support is terminated.
In Japanese Unexamined Patent Application Publication No. 2004-291866, it is described that if the amount of deviation of the current position from the initially set route has reached a predetermined value, a route to the target parking position is calculated again according to the steering angle and a relative positional relation, between the current position and the target parking position, at the time of calculation of the route.
In Japanese Unexamined Patent Application Publication No. 2004-338638, it is described that the amount of control delay during steering is estimated or detected and a travel route is set by setting the amount of change in turning curvature with respect to the distance traveled in consideration of the estimated or detected amount of control delay.
In Japanese Unexamined Patent Application Publication No. 2015-214223, it is described that data on a backing start position at which the vehicle starts to move backward to a parking area and a final stop position in the parking area are stored in correspondence to the parking area data that has been set in advance; the travel trajectory of the vehicle that moves backward from the backing start position to the final vehicle stop position and also turns during moving backward is corrected by using data on the relative positions of a detected obstacle and the vehicle, and calculates a corrected travel trajectory along which the vehicle moving backward does not encounter the obstacle.
In Japanese Patent No. 4092054, it is described that precise automatic parking is achieved by preventing deviation of the current position of a vehicle from a movement trajectory with the minimum time required for automatic parking.